Sea Floor Spreading


Vocabulary


mid-ocean ridge-undersea mountain chain where new ocean floor is produced
Sonar-system that determines the distance of an object under water by recording echoes of soundwaves
Sea-Floor Spreading-process in which molten material adds new oceanic crust to the ocean floor
deep-ocean trenchesdeep ocean valley along the ocean floor through which ocean crust slowly sinks into the Mantle
Subduction-oceanic crust sinks beneath the deep-ocean trench and back into the mantle at a convergent boundary

Outline


Mapping the mid-ocean ridge


      • mid-ocean ridge is the longest chain of mountains in the world
      • sonar is a device that bounces sound waves off under water objects and then records the echoes of these sound waves
Evidence for Sea-Floor spreading
    • Evidence from molten material
    • Evidence from Magnetic Stripes
    • Evidence from Drilling Samples

Subduction at deep-ocean trenches


      • deep-ocean trenches are deep undersea canyons
      • Subduction occurs at the deep-ocean trenches

Subduction and Earth's Oceans


    • Subduction in the Pacific Ocean
    • Subduction in the Atlantic Ocean